The technical field of the invention is that of engines containing pyrotechnical charges notably markers and smoke or illuminating cartridges launched from an aircraft to mark the location of a target in the water, for example, an enemy submarine or a boat in distress.
The pyrotechnical device, smoke or illuminating, launched from an aircraft to mark a target in the water can be launched by means of a rearwardly facing tube, for example, a pneumatic tube which imparts to the marker at the outlet of the tube a relative speed equal and in opposite direction to that of the aircraft such that the absolute speed of the marker is zero so that it will fall into the water at a vertical location below the point of launching. There can also be utilized as the tube, the barrel of the gun from which projectile is fired or any other means serving to contain and guide the projectile at the time of firing.
Problems are produced at the time of launching of such markers due to improper functioning of the propulsive system or an insufficiency of the propulsive charge whereby the marker has not left the tube and the pyrotechnical charge contained in the marker has been activated at the interior of the tube. This presents a grave danger to the launching aircraft.
There are known security arrangements intended to prevent the firing of the pyrotechnical charge when the projectile which transports it has not left the launch tube.
There is known, for example, arrangements comprising a spring-loaded finger which is ejected from its housing at the discharge of the projectile from the tube and which then actuates a delay device controlling the firing of the charge with a delay determined with respect to the passage of the projectile at the mouth of the launch tube.
The delay device is constituted, for example, by a receiver containing a divided product which travels in a determined time through an orifice which is opened by the ejection of the security finger. The divided product is constituted, for example, by balls.
Pyrotechnical delay relays are also known which control the detonation of a charge carried by the projectile with a determined delay with respect to the instance of commencement of the propulsion of the projectile, this being at the same time as when the relay is activated. The later arrangement does not offer any safety in the case when the projectile does not leave the launch tube.
There also exist primer delay relays whose activation is effected by the raising of a finger or by the acceleration imparted to the projectile.